What type of fuel does not burn easily due to being under six feet high?

Surface fuels refer to materials such as grass, shrubs, and small trees that are located at or near ground level and are characterized by their relatively low height, typically less than six feet. This type of fuel burns more easily and presents a greater risk for rapid fire spread compared to fuels that are higher off the ground.

The fact that surface fuels are typically under six feet does not inherently prevent them from burning; rather, it suggests they are often more accessible to flame and heat due to their position. In contrast, aerial fuels consist of materials such as branches and leaves that are higher up in the canopy, while ground fuels refer to organic matter that is found on or just below the surface of the ground, like peat or duff. Dead fuels, on the other hand, encompass any dead plant material, whether on the ground, under the surface, or in the air, but this classification doesn’t specifically address height or ease of ignition.

Thus, the characteristics of surface fuels, particularly their lower height and location, give them a unique impact on fire behavior compared to other fuel types.